1. Field of the Invention
The present invention relates to an illuminating device, particularly relates to a high power LED light source.
2. Description of the Related Art
As a new type of light source, LED gradually concerns all the countries in the world. Comparing with the traditional light source, LED involves the advantages: 1, having better safety, belonging to cold light source device, being driven in low voltage, having firm structure, not falling to pieces; having long useful life, lasting 50-100 thousand hours in a good heat dissipation condition, which is much longer than other light sources; 2, having rich colors, being regulated and controlled easily; 3, improving luminous efficiency greatly year after year, the general products achieving 60-801 m/w now, which is much better than incandescent lamps of 301 m/w, equaling 801 m/w of fluorescent lamp with best luminous efficiency, and to exceed the luminous efficiency of other light sources is just a matter of time; 4, protecting the environment, having no heavy metal pollutions in waste materials, according with the standard of EU ROSH.
As a semiconductor device, LED has the inherent disadvantage of not enduring heat. Especially for the high power device, if failed to conduct and emit the heat generated in working, the temperature of the PN junction will rise leading to the great dropping in luminous efficiency; if the temperature of the PN junction is over 120° C., with time passing by unrecoverable attenuation of light or even dying of the lamp will occur, and it is very common that after 1000 hours the brightness will decrease over 50%. A familiar LED light source structure, as illustrated in FIG. 1, comprises a chip bonding plane 01, a heat conducting pole 02, a heat dissipating substrate 03, and a user radiator 04. The structure comprises disadvantages that sectional area of the heat conducting pole 02 is small, the heat conducting path is long, and the thermal resistance is great. Commonly, silicone 05 is used to connect between the heat conducting pole 02 and the heat dissipating substrate 03, even if tin-lead solders were used, that will become a big thermal resistance region. For the thermal resistance is great, the structure can only conduct limited heat. So with the structure, only 1-3 W light source can be produced, and the light source of above 5 W will have short useful life due to absence of conducting heat.
In the mean time, conventional high power LED lamps usually use a metal shell as a radiator. If the power supply wire is led out from the inverse of the heat dissipating substrate, it can only be settled in the following two ways; 1, using a metal block thicker than the length of the lead wire as a transition between the heat dissipating substrate and the radiator, which will bring the thermal resistance and thermal accumulate to increase; 2, drilling and making insulation on the shell of the lamps, which will introduce problems of both appearance and waterproofness. So, setting the lead wire at the inverse of the heat dissipating substrate neither is convenient to fix, nor can make the combined area of the heat dissipating substrate and the user radiator up to 100%, which will weaken the heat dissipating effect.